21-orthoesters of cortical steroids and methods of preparing same

ABSTRACT

21-ORTHOESTERS OF 16A- AND 16B-HYDRO OR METHYL CORTICAL STEROIDS AND 21-ORTHOESTERS OF 16A,17A-CYCLIC ACETAL CORTICAL STEROIDS. THE METHOD OF PREPARING SUCH ORTHOESTERS COMPRISES REACTING THE CORRESPONDING 21-HYDROXY CORTICAL STEROID WITH AN EXCESS OF AN ALKYL ORTHOESTER IN THE PRESENCE OF A CATALYTIC AMOUNT OF A STRONG ACID. THESE 21-ORTHOESTERS OF CORTICAL STEROIDS HAVE UTILITY AS ANTIINFLAMMATORY AGENTS IN THE TREATMENT OF MAMMALS.

United States Patent 3,733,318 ZI-ORTHOESTERS 0F CORTICAL STEROIDS AND METHODS OF PREPARING SAME Michael Marx, Sunnyvale, Calif., assignor to Syutex Corporation, Panama, Panama No Drawing. Filed Mar. 23, 1972, Ser. No. 237,506 Int. Cl. C07c 173/00 US. Cl. 260--239.55 D 19 Claims ABSTRACT OF THE DISCLOSURE 21-orthoesters of 16mand 16 3-hydro or methyl cortical steroids and 21-orthoesters of l6a,l7a-cyclic acetal cortical steroids. The method of preparing such orthoesters comprises reacting the corresponding 21-hydroxy cortical steroid with an excess of an alkyl orthoester in the presence of a catalytic amount of a strong acid. These 21-orthoesters of cortical steroids have utility as antiinfiammatory agents in the treatment of mammals.

BACKGROUND OF THE INVENTION This invention relates to 21-orthoesters of cortical steroids and derivatives thereof and to methods of preparing such compounds. In a further aspect, this invention relates to 21-orthoesters of 161xand 16B-hydro or methyl cortical steroids, 21-orthoesters of 16a,l7u-CyCliC acetal derivatives of cortical steroids and the 6 and /or 9 and/or 11 position halogenated derivatives thereof, and to the methods of preparing such compounds.

Since the discovery of the valuable therapeutic properties possessed by cortical steroids, extensive research and activity has been focused upon these compounds. Exemplary of the compounds developed during such research are the cortical steroid 2l-monoesters (for example, see US. Pats. Nos. 2,842,567 and 3,048,581), the 2-orthocarbonate steroid derivatives (see U.S. Pat. No. 3,621,014) and the 17a,21-orthoesters of cortical steroids (for example, see Gardi et al., Tetrahedron Letters, 13, 448 (1961). As is obvious from their names, the orthoesters developed by prior workers, as exemplified by the 170:,21- orthoesters mentioned above, have two points of attachment to the steroid moiety, as opposed to the 2l-orthoesters of the present invention, to be described in detail below, which have but a single point of attachment of the orthoester moiety to the steroid moiety.

SUMMARY OF THE INVENTION The compounds of this invention are represented by the following formula:

wherein R is H, alkyl having from one to ten carbon atoms, cycloalkyl having 3 to carbon atoms, or aryl; R is alower alkyl having from 1 to 5 carbon atoms, or together the two R radicals form a monocyclic heterocyclic group having 3 or 4 carbon ring atoms; R is hydroxy or acyloxy having from 1 to 12 carbon atoms; R

3,733,318 Patented May 15., 1973 lice,

is H, u-methyl or fl-methyl, or R and it form together the group wherein R and R are independently selected from the group consisting of H, lower alkyls having from 1 to 5 carbon atoms, and aryl or together with the carbon atom to which they are joined R and R form a monocyclic alkyl group having 3 to 6 carbon atoms or a monocyclic heterocyclic group; when a double bond exists between C6 and (P7, Z is H, fluoro, chloro, or methyl and when a single bond exists between 0-6 and C-7, Z is where Z is H, fluoro, chloro or methyl Z is H or fluoro, but Z can be fluoro only when Z is fluoro; X is oxo or the group wherein R and R have the same meaning as set forth above, in the presence of a catalytic quantity of a suitable inert organic solvent. The resulting cortical steroid 21- orthoester is separated from the reaction mixture by any suitable technique or procedure such as, for example, thin layer or adsorption column chromatography, crystallization, and the like.

Formula I identified above encompasses, inter alia, two sub-groups, of 21-orthoesters of the present invention. These two groups are the l6u,17a-cyclic acetal-21- orthoester cortical steroids and the 16:1- or 1613-hydro or methyl-2l-orthoester cortical steroids of the present invention are represented by the following formula:

wherein R, R R R X, Y, Z, and the dotted bond lines are as defined above with respect to Formula I.

The 1604- and 16fl-hydro or methyl 21-orthoester cortical steroids of the present invention are represented by the following formula:

H OH

C=O OR wherein R is H, a-methyl, or fl-methyl; and R, R R, X, Y, Z, and the dotted bond lines are as defined above with respect to Formula I.

Obviously, in those compounds represented by Formulae I-III where a double bond exists between C-6 and C-7 in the steroid B ring, only a single Z substituent, which will be neither a or 13, but in the plane of the steroid moiety, will be possible.

As used herein, the following terms have the following meanings. The term lower alkyl refers to straight and branched aliphatic hydrocarbon groups containing from one to five carbon atoms and includes, for example, methyl, ethyl, isopropyl, n-butyl, s-butyl groups and the like. The term alkyl refers to straight and branched chain aliphatic hydrocarbon groups containing from 1 to carbon atoms and includes, for example, the aforementioned lower alkyl groups as well as groups such as, for example, hexyl, octyl, decyl, and the like. The term cycloalkyl refers to cyclic aliphatic hydrocarbon groups containing from 3 to 10 carbon atoms and includes such groups as cyclopropyl, cyclobutyl, cyclopentyl, and the like. The term aryl refers to groups containing at least one aromatic ring such as, for example, phenyl. Also encompassed Within the term aryl are substituted aromatic rings containing one or more substituent groups such as, for example, lower alkyls and/or halogens, and the like. The terms acyloxy and acyl derivatives refer to those esters and acyls conventionally employed in the cortical steroid art having from one to twelve carbon atoms, preferably being derived from carboxylic acids. Typical acyloxy groups, expresed as the ester, include for example, acetate, propionate, butyrate, valerate, caproate, enanthate, caprylate, acrylate, undecenoate, phenoxyacetate, benzoate, phenylacetate, diphenylacetate, diethylacetate, trimethylacetate, cyclohexylacetate, cyclopentylpropionate, and the like. The term monocyclic alkyl refers to saturated cyclic aliphatic hydrocarbons having from 3 to 6 carbon atoms, optionally substituted with methyl, ethyl or isopropyl groups. Typical monocyclic alkyls include, for example, cyclopropyl, cyclobutyl, cyclopentyl, 3,4-dimethyl cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-isopropylcyclohexyl, and the like. The term monocyclic heterocyclic refers to both saturated and unsaturated heterocyclic groups containing a single heterocyclic ring having from 4- to 6-ring atoms including at least one noncarbon ring atom selected from the group consisting of oxygen, sulfur, and nitrogen. Typical monocyclic heterocyclic groups include, for example, tetra-hydropyranyl, tetrahydrothiopyranyl, N-methylpiperidinyl, and the like. Further, unless expressely stated to the contrary, all temperatures refer to degrees centigrade.

21-orthoesters of the present invention encompassed by Formula II above include, for example:

1lfi-hydroxy-l6a,17a-isopropylidenedioxy-pregn-4-ene- 3,20-dione 2l-methylorthoformate;

1 1fi-hydroxy-16a, 17a-isopropylidenedioxy-pregna-1,4-

diene-3,20-d o e z-me hyl rthoform te;

16a,17a-isopropylidenedioxy-pregn-4-ene-3 ,11,20-trione 2 1 -methylorthoformate; 16a,l7a-isopropylidenedioxy-pregna-1,4-diene-3,l 1,20-

trione 2l-methylorthoformate; 6a-fluoro-llfi-hydroxy-l6a,17a-isopr0pylidenedioxypregna-l,4-diene-3,20-dione 2l-methylorthoformate; 6a-fiuO1O-1 lB-hydroxy-l6a,17a-isopropylidenedioxypregna-4-ene-3,20-dione 2l-methylorthoformate; 6a,9a-difluoro-l l B-hydroxy-l6a, l 7a-isopropylidenedioxypregna-1,4-diene-3,20-dione 2 l-methylorthoformate; 6a,9a-difiuoro-l lfi-hydroxy-l6a,17a-isopropylidenedioxypregna-4-ene-3,20-dione 21-methylorthoformate; 913,1lfl-dichloro-6a-fluoro-1611,]7a-isopropylidenedioxypregnal ,4-diene-3,20-dione 21-methylorthaformate; 16a,l7a-isopropylidenedioxy-pregn-l,4,6-triene-3,11,20-

trione 21-methylorthoformate; 9a-chloro-16a,17a-isopropylidenedioxy-pregna-1,4-,-6-

triene-3,1 1,20-trione 2 l-methylorthoformate; 6a,9a-difluoro-1 lfl-hydroxy-16a,l7a-isopropylidenedioxypregna- 1 ,4,6-triene-3 ,20-dione 2l-methylorthoformate; 6a-fluoro-16a,17a-isopropylidenedioxy-pregna-1,4-diene- 3,1 1,20-trione 21-methylorthoformate; 6a-flu0ro-16a,17a-isopropylidenedioxy-pregna-4-ene- 3,1 1,20-trione 21-methylorthoformate; 6a,9a-difiuoro-l6a,17a-isopropylidenedioxy-pregna-1,4-

diene-3,1l,20-trione 21-methylorthaformate; 6a,9a-difiuoro-16a,17a-isopropylidenedioxy-pregna-4- cue-3,1 1,20-trione 21-methylorthaformate; 911,1IB-dichloro-fia-fluoro-l6a,17u-isopropylidenedioxypregna-1,4-diene-3, 1 1,20-trione 21-methylorthoformate; 1 lfi-hydroxy-l6a,17a-methylenedioxy-pregna-4-ene- 3,20-dione 21-ethylorthaforrnate; 1 lfl-hydroxy-16a,17a-methylenedioxy-pregna-1,4-diene- 3,20-dione 2l-ethylorthaformate; 16a, 1 7a-methylenedioxy-pregn-4-ene-3 ,11,20-trione 21- "ethylorthaformate; 16a,17a-methylenedioxy-pregna-1,4-diene-3,1 1,20-trione 21-ethylorthoformate; 6a-fiuoro-l 1,6-hydroxy-16a,17a-methylenedioxy-pregna- 1,4-diene-3 ,20-dione 21-ethylorthoforrnate; 6a-fill01'0-1 lfi-hydroxy-l6a,17a-methylenedioxy-pregn- 4-'e'ne-3,20-dione 2 l-ethylformate 60:,9oZ-difiUOfO-l 1fl-hydroxy-16a, 17a-methylenedioxypregna- 1 ,4-diene-3 ,20,-dione 21-ethylorthaformate; 66:,9a-difill0IO-l lfi-hydroxy- 16m, 17a-methylenedioxypregn-4-ene-3,20-dione 21-ethylorthoformate; 9,1lB-dichloro-6a-fluoro-16a,17a-methylenedioxy pregnal,4-diene-3,20-dione 2l-ethylorthoformate; 16a, 1 7a-methylenedioxy-pregn 1 ,4,6-triene-3 ,11,20-

trione 21-ethylorthoformate; 9a-fiuoro-l6a,17a-methylenedioxy-pregna-1,4,6-triene-3,

1 1,20-trione 2 l-ethylorthoformate; 6,9a-difiuoro-1 1B-hydroxy-16a,17a-methylenedioxypregnal,4,6-triene-3,20-dione 2 l-ethylorthoform ate; 6a'-fiu01'0-16u, 17a-methylenedioxy-pregna-1,4-diene- 3,11,20-trione 2l-ethylorthoformate; 6a-fluoro-l6a,17u-methylenedioxy-pregn-4-ene-3,11,20-

trione 2l-ethylorthoformate; 6a,9a-difiuoro-16a,17-methylenedioxy-pregna-1,4-diene- 3,11,20-trione 2l-cthylorthoformate; 6,9wdifluoro-16a,17a-methylenedioxy-pregn-4-ene-3,

11,20-trione 21-ethylorthoformate; 911,1lfi-dichloro-6a-fiu0ro-16u,17a-methylenedioxypregna-l,4-diene-3,1 1,20-trione 2 l-ethylorthoformate; 11fi-hydroxy-l6a,17a-(3'-pentylidenedioxy)-pregn-4-ene- 3,20-dione 2l-isopropylorthobenzoate; 11,'B-hydroxy-16a,17u-(3 -pentylidenedioxy )-pregna-1,4-

dieiie-3,20-dione 21-isopropylorthobenzoate; 16a, 17(1-(3 '-pentylidenedioxy)-pregn-4-ene-3,11,20-

trione 21-isopropylorthobenzoate; 16a,17a-(3'-pentylidenedioxy)-pregna-1,4-diene3,11,20-

trione 2l-isopropylorthobenzoate; 6a-fluoro-11fi-hydroxy-16a,17a-(3 'pentylidenedioxy pregna-l,4-diene-3,20-dione 21-isopropylorth0benzoate;

HzCOCH(OCHs)3 6a,9a,difiuoro 11B hydroxy-lGamethyl 17a penta-noy-loxypregm1 1,4 diene 3,20 dlone 21- HaCOCHKOCHa):

90. fiuoro 11B hydroxy 1%- methyl 17apentanoyloxy-pregna- 1,4-diene 3,20 dlone 21-methy1- 90. chloro 11B hydroxy-lGB- methyl-17a proplonyloxy-pregna- 1,4 diene 3,20-dione ZI-methylortho formate orthoformate 2l-orthoester cortical steroids of the present invention encompassed by Formula III also include, for example, those compounds corresponding to the 16u-methyl or 16 3- methyl compounds listed above wherein a hydrogen atom is substituted for either the 16u-methy1 group or the 16/3-methyl group. Of particular interest in this group are:

11,8,17 a-dihydroxy-pregna-1,4-diene-3,20-dione 21-methylorthoformate;

115,l7u-dihydroxy-pregna-1,4-diene-3,20-dione 21-ethylorthoformate;

9u-flu0rO-1 1 p,l7a-dihydroxy-pregna-1,4-diene-3,20-

dione-Zl-methylorthoformate;

9a.-flI.101'O-1 1,3,17u-dihydroxy-pregna-l,4-diene-3,20-

dione-Zl-ethylorthoformate;

Ga-flHOIO- 1 1p, 17ia-dihydroxy-pregna-1,4-diene-3 ,ZO-dione 21-methylorthoformate;

6a-fluoro-l 1 9,17a-dihydroxy-pregna-l,4-diene-3,20-dione 21-ethylforthoformate;

9u,l 1 p-dichloro-17'a-hydroxy-pregna-1,4-diene-3,20-

dipne ZI-methylorthoformate; and

9:1,11 fi-dichloro-l7a-hydroxy-pregna-1,4-diene-3,20-dione 2l-ethylorthoformate;

The process of preparing the 21-orthoesters compounds of this invention is represented by the following schematic overall reaction equation:

HzCOH 6a-fiuo ro 11B-hydroxy-16a-methyl 17a=pentanoy1oxy-pregna-1,4- dlene 3,20 diene 21-methyl- Acid catalyst R OH wherein R, R R R X, Y, Z, and the dotted bond lines have the same meanings as set forth above.

The above reaction can be conveniently efiected, according to this invention, by reacting a 2l-hydroxy cortical steroid corresponding to the 2l-orthoester cortical steroid desired, with a suitable orthoester corresponding to the orthoester group desired, in the presence of a suitable strong acid. The strong acid acts only as a catalyst and. thus only a catalytic quantity of the acid is required. Suitable strong acids include, for example, perchloric acid, p-toluenesulfonic acid, sulfuric acid, benzenesulfonic acid, and the like.

Although only one mole of the orthoester is stoichiometrically required for reaction with one mole of the 21- hydroxy cortical steroid, it has been found that in order to obtain suitable yields, an excess of the orthoester reactant should be used. Conveniently, the orthoester exchange is carried out by allowing a suspension or solution of the appropriate 2l-hydroxy cortical steroid in the undiluted orthoester reagent to react in the presence of an acid catalyst. Alternately, the reaction mixture may consist in part of an inert solvent, e.g. benzene, which serves the dual purposes of bringing the steroid reactant into solution as well as permitting the use of a smaller quantity of the relatively costly orthoester reagent. Reaction temperatures may range from below 0 to the boiling point of the particular solvent-reactant system being employed, but it is operationally convenient to work at or near room temperature. Reaction times may vary over a Wide range, from a few minutes to 18 hours or more, depending upon the particular steroid substrate, the orthoester reagent, the mole ratio of orthoester reagent to steroid reactant, the nature and concentration of the acid catalyst employed, and the reaction temperature. The progress of the orthoester exchange reaction is conveniently monitored by thin layer chromatography, and by employing this monitoring technique an optimum combination of the reaction variables enumerated above can be determined by routine experimentation for each steroid-orthoester reaction.

In a useful modification for these reactions where the steroid substrate does not have a free l7a-hydroxy group, the reaction may be conducted in a suitable inert organic solvent, for example, benzene, having a boiling point equal to or greater than the alkyl alcohol byproduct (i.e., R OH) thereby permitting the easy removal of the alkyl alcohol during the reaction by conducting the reaction at a temperature above the boiling point of the alkyl alcohol, but below the respective boiling points of the solvent, the orthoester reactant, the 2l-hydroxy steroid substrate and the 21-orthoester compounds of this invention.

The desired 21-orthoester corticosteroid is subsequently recovered from the reaction mixture by any suitable procedure such as, for example, evaporative concentration, crystallization or thin layer or adsorption column chromatographic separation and purification.

The 2l-hydroxy steroid substrate and orthoester starting materials used in preparing the 21-orthoester compounds of this invention can be prepared according to known procedures and in some instances are commercially available. Additional information concerning the preparation of 2l-hydroxy steroids suitable for use in the preparation of the compounds of Formula 11 above can be obtained, for example, from US. Pat. Nos. 3,048,581, and 3,126,375; and from Fried et al., J. Am. Chem. Soc., 802,338 (1958) and Mills et al., J. Am. Chem. Soc., 82, 3399 (1960). Additional information concerning the preparation of 2l-hydroxy steroids suitable for use in the preparation of the compounds of Formula III above can be found, for example, in US. Pats. Nos. 2,894,963; 3,013,- 033; and 3,119,748; and in Edwards et al., Proc. Chem. Soc. (London), p. 87 (1959), Edwards et al., J. Am. Chem. Soc., 82, 2318 (1960), and Taub et al., J. Am. Chem. Soc., 80, 4435 (1958). Information concerning the preparation of the orthoester starting materials can be found, for example, in Organic Syntheses-Collective Volume I, ed. by Gilman and Blatt (2nd edit.) p. 258- 261, N.Y., Wiley (1941) and references cited therein.

The 21-orthoester cortical steroids compounds of this invention exhibit anti-inflammatory activity in mammals, and can be administered to mammals for the treatment of inflammation in the same manner as the parent 21-hydroxy compounds such as, for example, fluocinolone acetonide (i.e., 6a,9a-difiuoro-11fl-hydroxy-16a,17a-isopropylidenedioxy-l,4-pregnadiene-3,20 dione). Further information concerning the application of fluocinolone acetonide, and correspondingly the compounds of this invention, can be had by reference to the 1972 addition of the Physicians Desk Reference published by Medical Economics, Inc.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following specific description is given to enable those skilled in this art to more clearly understand and practice the present invention. It should not be considered as a limitation upon the scope of the invention but merely as being illustrative and representative thereof.

Examples 1-8 illustrate methods according to this invention for preparing compounds of Formula II, for ex- 16 ample, those compounds listed in column 3, line 72, through column 6, line 75 hereof.

Examples 9-14 illustrate methods according to this invention for preparing compounds of Formula III, for example, those compounds listed on page 11, line 19 to page 26, line 16 hereof.

EXAMPLE 1 A stirred suspension of 0.100 g. of 6a,9a-difluOrO 113,21-dihydroxy 16:1,1711 isopropylidenedioxy-pregna- 1,4-diene-3,20-dione in 10 m1. of trimethyl orthoformate is treated with 2 drops of a solution containing 0.5 ml. of 70% aqueous perchloric acid in 19.5 ml. of ethyl acetate. Stirring i continued for 1 hour during which time a clear solution results. The reaction mixture is brought to an alkaline pH by addition of an aqueous sodium bicarbonate solution and is extracted with diethyl ether. The organic extracts are washed successively with saturated aqueous sodium bicarbonate solution, water, and saturated brine. 2 drops of triethylamine are added to the extracts to assure basicity. The extracts are dried over anhydrous potassium carbonate and the solvent is evaporated under reduced pressure. The residue is recrystallized from acetone-hexane which contains a drop of triethylamine. There is obtained crystalline 60:,9a-difil10i0- llfl-hydroxy 1611,170: isopropylidenedioxy-pregna-1,4- diene-3,20-dione Zl-methylorthoformate.

EXAMPLE 2 A suspension of 0.130 g. of 9a-fluoro-1lfi,21-dihydroxy- 16a,l7a-isopropylidenedioxy pregna-l,4-diene-3,20-dione in 10 ml. of ethyl acetate is treated with 2 m1. of triethyl orthoformate and 5 drops of a solution of 0.25 ml. of 70% aqueous perchloric acid in ml. of ethyl acetate. The mixture is stirred at room temperature for 17 hours, at which time the clear reaction solution is poured into aqueous sodium bicarbonate. Following the remainder of the procedure of Example 1, there is obtained 9a-fl-U01O- llfl-hydroxy l6a,l7a isopropylidenedioxy-pregna-1,4- diene-3,20-dione 2 l-ethylorthoformate.

EXAMPLE 3 A solution of 0.200 g. of 9a,llB-dich1oro-6a-fiuoro-2lhydroxy-16a,17a-isoproylidenedioxy-pregna 1,4 diene- 3,20-dione in a mixture of 15 ml. of 1,4-dioxane and 10 ml. of benzene is treated with 4 ml. of triethyl orthoacetate and 10 mg. of p-toluenesulfonic acid. The reaction mixture is stirred and heated at the boiling point for 3 hours, during which time approximately 8 ml. of distillate is collected. After being allowed to cool, the reaction mixture is poured into an aqueous sodium bicarbonate solution and extracted with methylene chloride containing a few drops of triethylamine. The crude residue obtained after evaporation'of the solvent is purified by thin layer chromatography on silica gel employing a 60% acetone- 40% hexane developing system. There is obtained 911,115- dichloro 6oz fiuoro-16a,17a-isopropylidenedioxy-pregna- 1,4-diene-3,20-dione 2l-ethylorthoacetate.

EXAMPLE 4 A suspension of 0.140 g. of 6a,9a-difiuoro-2l-hydroxy- 16a,l7a-isopropylidenedioxy-pregna 1,4 dime-3,11,20- trione in 15 ml. of benzene is treated with 2 ml. of 2- methoxy-1,3-dioxolane and 5 mg. of p-toluenesulfonic acid. The mixture is stirred and heated at the boiling point while a total of 6 ml. of distillate is collected during 2 hours. After being allowed to cool to room temperature, the reaction mixture is treated in accordance with the remainder of the procedure of Example 3. There is obtained 6a,9a-difiuoro 16a,17a isopropylidenedioxypregna-1,4-diene-3,l1,20-thione 21-cyclic ethylene orthoformate.

EXAMPLE 5 Following the procedure of Example 2 using 115,21-di- Y y-6e"fl .1QI9 :,17ot isopropylidenedioxy-pregnav 17 1,4-diene-3,20-dione and trimethyl orthoformate as the reactants, there is obtained 60: fluoro 11p hydroxy- 160:,17u isopropylidenedioxy-pregna 1,4 diene 3,20- dione 21-methylorthoformate.

EXAMPLE 6 EXAMPLE :7

Following the procdure of Example 1 using 115,21-dihydroxy-16a,17ot-isopropylidenedioxy-pregna 1,4 diene- 3,20-dione and trimethyl orthoformate as the reactants, there is obtained l1B,dihydroxy-l6u,l7a-isopropylidenedioxy-pregna-1,4-diene-3,20-dione 2l-rnethylorthoformate.

EXAMPLE 8 Following the procedure of Example 1 using 1119,21- dihydroxy-9a-fluoro 16,l7ot isopropylidenedioxy-pregna-1,4-diene-3,20-dione and trimethyl orthoformate as the reactants there is obtained 90; fiuoro 11,8 hydroxy- 16a,17a-isopropylidenedioxy-pregna-l,4-diene-3,20 dione 2l-methylorthoformate.

In a similar manner to the methods of Examples l-4, using reactants as dictated by the particular steroid 21- orthoester desired, the compounds listed on page 6, line 11 to page 11 line 18 can be prepared.

EXAMPLE 9 A stirred slurry of 0.200 g. of 6 ,9a-difluoro-l1/3,17a, 21-tr ihydroxy-lfia-methyl-pregna-l,4-diene-3,2O dione in 50 ml. of trimethyl orthoformate is treated with 25 drops of a solution containing 0.5 ml. of 70% aqueous perchloric acid in 200 ml. of ethyl acetate. After being stirred for 18 hours at room temperature, the mixture is filtered to separate unreacted starting material. The filtrates are treated with an excess of aqueous sodium bicarbonate followed by extraction with diethyl ether. The extracts are washed successively with aqueous sodium bicarbonate, water, and saturated brine, dried over anhydrous potassium carbonate to which there has been added 2 drops of triethylamine, and evaporated to dryness under reduced pressure. The crude crystalline residue so obtained is purified by preparative thin layer chromatography on silica 'gel employing a 5%;acetone-95% chloroform eluant system. There is. obtained crystalline 611,90:- difluoro 1118,1701 dihydroxy 16a methyl-pregna'lA- diene-3,20-dione 21-methylorthof ormate.

EXAMPLE A suspension of 0.085 g. l1fi,2l-dihydroxy-9a-fiuoro- 16fi-methyl-17a-pentanoyloxy-pregna-1,4-diene 3,20 dione in 8 ml. of ethyl acetate is treated with 1 ml. of trimethyl orthoformate and 3 drops of a solution of 0.25 ml. of 70% aqueous perchloric acid in 100 ml. of ethyl acetate. After stirring for 2 hours at room temperature, the now-homogeneous solution is poured into an aqueous sodium bicarbonate solution. Following the remainder of the procedure of Example 9, there is obtained 9a-fluoro-1lfihydroxy-16p-methyl-17a-pentanoyloxy-pregna-1,4 diene- 3,20-dione 21-methylorthoformate.

EXAMPLE 11 A suspension of 0.110 g. of 6a,9a-difiuoro-l6a-methyl- 11B,17a,2l-trihydroxy-pregna-1,4-diene-3,20-dione in 8 ml. of ethyl acetate is treated with 1.5 ml. of 2-methoxy-1,3- dioxolane and 6 drops of a solution containing 0.25 ml. of 70% aqueous perchloric acid in 100 ml. of ethyl acetate. After stirring for 1 hour at room temperature, the homogeneous solution is poured into aqueous sodium bicarbonate solution. Following the remainder of the procedure of Example 9 utilizing thin layer chromatography 18 on silica gel employing a 90% chloroform-10% acetone developing solvent system, there is obtained 6u,9a-difluoro- 1lp,l7a-dihydroxy-lfia-methyl-pregna-1,4-diene-3,20 dione 2l-cyclic ethylene orthoformate.

EXAMPLE 12 Following the procedure of Example 9 using 16ot-methyl- 6a,6;8,9u-trifluoro-l1B,17a,2l-trihydroxy-pregna 1,4 diene-3, 20-dione and trimethyl orthorformate as the reactants, there is obtained 11,3,17a-dihydroxy-16a-methyl-6a, -6fl,9a-trifluoro-pregna-l,4-diene-3,20 dione 21 methylorthoformate.

EXAMPLE 13 Following the procedure of Example 11 using 6a,90tdifluoro-11,8,2l-dihydroxy-16ot-methyl-17a pentanoyloxypregna-l,4-diene-3,20-dione and trimethyl orthoformate as the reactants, there is obtained 6a,9a-difluoro 115 hydroxy-l6a-methyl-l7a -pentanoyloxy-pregna-1,4-diene 3, 20-dione 2l-methylorthoformate.

EXAMPLE 14 Following the procedure of Example 10 using 11 3,21- dihydroxy-9a-chloro-l6fl methyl 17a propionyloxypregna-l,4-diene-3,20-dione and trimethyl orthoformate as the reactants, there is obtained 9a-chloro-l lp-hydroxy-l6fimethyl-17a-propionyloxy-pregna-l,4-diene-3,20-dione 21- methylorthoformate.

In similar manner to the methods of Examples 9-11, using reactants as dictated by the particular steroid 21-orthoester desired, the compounds listed on page 11, line 19 to page 26, line 16 can be prepared.

While the present invention has been described with reference to specific embodiments thereof, it should be understood by those skilled in this art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made .to adopt a particular situation, material or composition of matter, process, process step or steps, or then-present objective to the spirit of this invention without departing from its essential teachings.

What is claimed is:

1. A compound having the formula:

. wherein R is H, alkyl having from one to ten carbon wherein R and R are independently selected from the group consisting of H, lower alkyls having from 1 to 5 carbon atoms, and aryl or together with the carbon to which they are joined Rt and R form a monocyclicalkyl group having 3 to 6 carbon atoms or a monocyclic heterocyelic 19 group; when a single bond exists between C-6 and -7,

Z represents Z1 ZI where Z is H, fiuoro, chloro, or methyl, and Z is H or fluoro, but Z can be fluoro only when Z is fluoro, and when a double bond exists between C6 and C-7, Z is H, fluoro, chloro, or methyl; X is 0x0 or the group H... I wherein R is hydroxy, fluoro, or chloro; Y is H, fiuoro, or chloro, but when R is fiuoro, Y is either H or chloro; and the dotted bond lines between the 1- and 2-position of the steroid A ring and the 6- and 7-position of the steroid B ring indicate either a single or a double bond.

2. The compound of claim 1 having the formula:

R OR.

wherein R, R R R X, Y, Z, and the dotted bond lines are as defined in claim 1.

3. The compound of claim 2 wherein said compound is 60,9oc-difll101'O-l1}3-hyd10Xy-16a,17a isopropylidenedioxypregna-1,4-diene-3,20-dione 21-methylorthoformate.

4. The compound of claim 2 wherein said compound is Ga-flllOI'O-l 1,8 hydroxy 160:,170: isopropylidenedioxypregna-l,4-diene-3,20 dione 21-methylorthoformate.

5. The compound of claim 2 wherein said compound is 90:,11B-di6h101'0-6oc-fl11010 16a,17a isopropylidenedioxypregna-l 4-diene-3,20-dione 21-methylorthoformate.

6. The compound of claim 2 wherein said compound is 11fi-hydroxy-16a,17a-isopropylidenedioxy-pregna 1,4- diene-3,20-dione 21-methylorthoformate.

7. The compound of claim 2 wherein said compound is 9oc-fl11010-11 fi-hydroxy-16u,17u isopropylidenedioxypregna-1,4-diene-3,20-dione 21-methylorthoformate.

8. The compound of claim 1 having the formula:

R OR

HzCOC 20 wherein R is H, a-methyl or fl-methyl; R, R R X, Y, Z and the dotted bond lines are as defined in claim 1.

9. A compound of claim 8 wherein said compound is 9a-fluoro-115-hydroxy 16B methyllh-pentanoyloxypregna-l,4-diene-3,20-dione 21-methylorthoformate.

10. A compound of claim 8 wherein said compound is 9a-chloro-1lB-hydroxy 16/3 methyl 17a propionyloxy-pregna-1,4-diene-3,20-dione 2l-methylorthoformate.

11. A compound of claim 8 wherein said compound is 6a,9a-difiuoro-1lfl-hydroxy 16oz methyl-17a-pentanoylpregna-1, diene-3,20-dione 21-methylorthoformate.

12. The compound of claim 8 wherein said compound is 6a-fluoro-11B-hydroxy 16a methyl 17a pentanoyloxy-pregna-l, 4-diene-3,20-diene 2l-methylorthoformate.

13. A compound of claim 8 wherein said compound is 6a,6}3,9oz trifiuoro 115,170 dihydroxy 16oz methylpregna-l,4-diene3,20-dione 21-methylorthoformate.

14. The compound of claim 8 wherein said compound is 6a.9u difiuoro 113,170 dihydroxy 16a methylpregna-1,4-diene-3,20-dione 21-methylorthoformate.

15. A process for preparing the compounds of claim 1 which comprises reacting a 21-hydroxy cortico steroid with an orthoester having the formula:

/OR Ii.-C---OR wherein R and R are as defined in claim 1, in the presence of a catalytic quantity of a strong acid.

16. The process of claim 15 wherein the reaction is conducted in an excess of said orthoester reactant.

17. The process of claim 15 wherein the reaction is conducted in the presence of an inert organic solvent.

18. The process of claim 15 wherein said strong acid is selected from the group consisting of perchloric acid, p-toluenesulfonic acid, sulfuric acid and benzenesulfonic acid.

19. The process of claim 15 wherein the reaction is driven to completion by distillation from the reaction mixture of the alcohol byproduct R OH.

References Cited UNITED STATES PATENTS 3,422,193 1/ 1969 Shapiro et a1 424243 3,464,980 9/ 1969 Bruce 260239.55 3,621,014 11/1971 Stache ct a1. 260239.55

HENRY A. FRENCH, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3, 733,318

DATED May 15, 1973 |NVENTOR(S) 1 Michael Marx It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In columns 5 and 6, in formula (IIc) H COCH(OCH 2 H CQCH(OCH 2 C should read C=O At the bottom of column; 6, in formula (IIe) C=O should read C=O t the bottom of column 6, in formula (IIe) CH CH CH should read CH Signed and Sealed this twenty-eight Day of October 1975 [SEAL] A ttes t:

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner oj'latents and Trademarks 

